A public health crisis, such as a bioterrorist attack or an epidemic, would be difficult for health officials to identify in the early stages. For instance, biological agents can be secretly released by terrorists in a community and potentially kill hundreds of thousands in a relatively short period of time, but they are often extremely difficult to detect in the environment. A successful attack with biological agents, such as anthrax, smallpox, or bubonic plague, might only become clear days later, after many people in a community have become seriously ill and are beyond the help of available medical treatments. Further, many biological agents are highly contagious, so that if there is a time lapse before health officials recognize an attack, victims can multiply the harmful effects by spreading the disease to others.
Thus, early detection of a public health crisis will be critical to saving lives. The sooner a bioterrorist attack or epidemic is detected, the sooner an assessment of such an event can be completed, and the sooner medical care can be administered to those exposed. People today are incredibly mobile, commuting in an out of urban centers on a daily basis and traveling all over the world regularly. Failure to detect an outbreak of a contagious disease at the outset could result in its rapid spread. Therefore, there is a need in the art for an effective surveillance system to provide an early warning of unusual outbreaks of disease or other public health crises, whether natural or intentional.